Arrangement for measuring electric energy in short duration time intervals



Feb. 16, 1954 AVERSTEN 2,669,638

ARRANGEMENT FOR MEASURING ELECTRIC ENERGY IN SHORT DURATION TIME INTERVALS Filed March 13, 1950 INVENTOR 16$? E Aim 17 J5 BY ATTORNEY Patented Feb. 16, 1954 ARRANGEMENT FOR MEASURING ELECTRIC ENERGY IN SHORT DURATION THWE IN- TERVALS Karl J. Aversten, Lidingo, Sweden, assignor to Svenska Aktiebolaget Gasaccumulator, Lidingo, Sweden, a corporation of Sweden Application March 13, 1950, Serial No. 149,434

Claims priority, application Sweden December 16, 1949 2 Claims.

In electric welding processes of short duration, as in spot, plug, stud, butt or flash welding or similar processes, use is made of various types of control devices for allowing the passage of the welding current only for the time required for a satisfactory weld. Such devices are usually provided with adjusting arrangements for adjusting the interval after which it is desired that the device should break the current. For instance, a relay may be adapted to actuate, at the end of the interval referred to, a circuit breaker. The operation of such devices is based on the assumed constancy of the rate at which energy from the current source is consumed at the welding point. If, however, the current source supplies energy at a varying rate and the length of the interval is kept constant it is not possible to ensure a satisfactory weld, for the variations in power referred to may cause the amount of melt produced at the welding point to be too great or too small.

According to the present invention the length of the interval is controlled in dependence upon the power consumed, so that if the power decreases the length of the interval will increase and vice versa, whereby a constant amount of energy is applied to the weld. This is achieved, according to the invention, by applying the current through a conductor which is suitably proportioned with regard to the energy to be applied in such a way as to melt off when this amount of energy has passed through it, thereby breaking the current.

The invention will be set forth in more detail in connection with the drawings, showing some embodiments thereof. Fig. 1 is a schematic diagram of a welding arrangement according to the invention, Fig. 2 shows, in elevation, part of the arrangement after a welding operation has been completed, Fig. 3 a vertical section corresponding to Fig. 2, and Fig. 4 shows the relative positions of some details of the arrangement during the preparation of a subsequent welding operation.

As shown in Fig. 1, a workpiece l and an electrode 2 are included in a circuit with a conductor 3, a battery 4 and a switch 5. The circuit further comprises a pair of spring-urged contact blocks 6 and l and a similar pair of blocks 8 and 9, spaced from the first pair. A comparatively fine-gage fuse wire In of silver, copper or the like is wound on a drum H and extends between the blocks as shown, the wire thus carrying the current flowing in the circuit.

The arrangement operates as follows. when switch 5 is closed and electrode 2 brought near to the workpiece, current passes from battery 4 through conductor 3, blocks 6 to 9, wire I0, conductor 3, electrode 2 and the workpiece. If the electrode 2 is removed slightly from the work an arc is struck and produces the heat energy required for the weld, whereupon the electrode may be attached to the work by pressure.

The wire it should be of sufficiently fine gage that the heating of the wire portion between the pairs of blocks is sufficient for bringing the midportion of the wire to melting, thereby rupturing the wire and cutting off the current. By suitable choice of the gage of wire it is possible to determine the time required for the wire to rupture. To ensure a satisfactory weld, it is required to apply a predetermined amount of energy to the welding area. If this amount is either too great or too small, the quality is impaired. The correct gage to be used is that which allows the correct amount of energy to be developed. If standard type control devices are used, which cut off the current after a predetermined interval, the weldin process will be dependent upon possibly occurring fluctuations in the current applied, so that, for instance, if the current is lower than the expected value, the amount of energy applied is too small, thus impairing the weld. According to the invention, however, the current is interrupted in depen ence upon the amount of energy applied, i. e. if the power consumed in the welding area is altered, the time required until the wire ruptures, and therefore the welding interval, varies accordingly so as to make the amount of energy applied have a uniform value Since the wire rupture breaks the circuit, switch 5 is required only for closing it. No inconvenience is therefore caused by arcing at the breaking of the current, wherefore switch 5 may be of lighter construction than if it had to serve also for breaking, as in ordinary type devices. This is of particular importance in portable devices.

The electrode 2 may comprise a stud or the like to be attached to the work, for which case the stud may be supported and handled by means of a welding gun having an integral switch replacing switch 5 in Fig. 1.

The fuse wire I 0 may be of practically any metal obtainable with uniform electric properties. However, as the arrangement is preferably intended for use at high amperage currents, the wire should have low resistance in order to keep down dimensions.

adjusting 'peg l movable inaslotnl fiiprovided; in a fixed plate ll in such a waythat-th'e-spacing between the pairs of blocks may be adjusted by means of peg I5. On the lowermost part... of

block 6 there is provided .a jaw l8, whiclrisl adapted, when the pairs of blocks are broughttogether, to enter within extension I 4 of spring 13 and thereby urge blocks 8 and 9 apart. "Jaw l8' further has a notch l9 allowing passage .oilzthe; end of extension I4.

When the operator desires to perform a second welding operation, upon rupture of wire" in, he grips adjusting peg I5 and by means of it displaces; blocksz'fi and 1'? to. 'the; left' asviewed in; Figs .12 and. 3x Jaw I8: thenienterswithin ex-: tensioni l and. forces:..spring xlsioutwardl thus urging blocks18 and!) apart, which-causes. the stump .of wire; .i 2. to; drop. out. Further: displace mentrof: blocks: E'and '3 brings: the .free end of wire it) between. thezopen .pair of blocks'B. and 9 and when HOT/0111911215 reached extension Hi; this moves; into the .notch,: the blocks'8 and G e-re brought together and. thewire end. is locked be tween them'asillustratedin Fig. Blocks Band dare. assumed toexert more. pressuresonthewire than blocks" 5 and 1, .=so..that when these are moved to:the right to the end. position-shown in Figszyl to; 3 the wirexremains locked by. blocks: 8and 9.. Wire, leiszthentautened and a predetermined length thereof .is included in the.we1cling current circuit. The. preparation ofuthie arrangement for a. subsequent weld isthus .performed: simply by asingle toand :fromovement. ofiadjustingpeg 55'.

The: gage of; wiredflj must be determined' -bytests: made-beforehand, so as to: make it suitable for. the: amperage and. type of welding operation desi1:ed;-.: Thisisfeasiblasince ordinarily'a numbe'r oi-simi-lar weldsiare. to .bemadet The: wire may be replaced by a thin ribbon. This provides a simple meansxby which to .vary 'theamountof energy-allowed to pass by the ribbon before rup-.= turing.

The, control arrangementthas been shown in-- cluded in; the welding current. circuit. Irr alternating-ourrentwelding atransformer may be used tothe'prirnary of which is applied'high-voltage low-amperage "current and. the: secondary of" which delivers low-voltage. high-amperage curarent. The control arrangement may then be included in circuit with the primary whereby small dimensions, may. be ensured... ,Further. modificationsof the. arrangement are possible within the scope of the invention. For instance, the arrangement may be used not only for welding pur- V poses but in any case where it is desired to allow the passage; of a :predetermined amount of energy-.duringxashort interval.

What is claimed-is:

1. An arrangementfor determining the time fOnareweldingduring short time intervals compr ising;;.;a,yvelding: .circuit, a fusible conductor disposed in said circuit, means for supplying ele'ctric energy to said circuit so that all electric energysupplied for welding will pass through said-conductor, said conductor having a resistivity and being dimensioned so as to reach, after the passage therethrough of the electric energy for welding, a temperature sufilcient to cause rupture by melting,- and two. pairsof contactmaking blocks,- each pair being adapted to grip;

saidconductor, and.-.one-. .or-. said' pairs; being.

adapted to exert a smaller grippingmressure: than the other-pairiand being displaceable rela.-. tivethereto, so as towary the spacing between said pairsof blocks.

2". "An arrangement for. determining thetime forarc welding duringshort. time intervals, com-.- prisingaa welding. circuit, av battery as adirect current source. in the welding'circuit-one ter-- minal of the. battery adapted.t0: be connected with the work and the otherterminal connected through a switchto a first pair .01" blocks, a fuseconductorupassingfrom said .first pairof blocks; tosa second'pair. of blocks, and a conductorfroma said second pair-of blocks to; a welding electrode-,- said fuse conductor having suclr dimensions-and.v resistivity with .regard .to thetamount. ofzelectrici energy :from' the .current'psource that the: 0011-.

ductor will fuse after a passagetherethrough of sufficientamount ofelectricenergy-for welding;

KARLJ. AVER'STEN .1 

